The twin blasts were followed by several hours of gunbattles between rebel fighters and regime forces in downtown Damascus. A reporter for an Iranian TV channel was killed by gunfire near the clashes, and a correspondent for another Iranian station was wounded.

The brazen rebel attacks in the heart of the Syrian capital highlighted their determination to bring down Assad as the country's civil war intensifies. It was the second day of bombings to shake the capital.

A Damascus school that activists said was being used by regime forces as a security headquarters also was bombed on Tuesday, wounding several people.

Near Damascus, two activist groups monitoring casualties said several dozen bodies were found Wednesday in a single location.

Syria's unrest began in March 2011 when protests calling for political change met a violent government crackdown. Many in the opposition have since taken up arms, and activists say the fighting has killed nearly 30,000 people.

Over the past few months, the rebels have increasingly targeted security sites and symbols of regime power in a bid to turn the tide in the fighting.

The rebels' Free Syrian Army claimed responsibility for Wednesday's bombings.

The blasts went off about 10 minutes apart, starting around 7 a.m., near the landmark Omayyad Square, and were heard several miles (kilometers) away.

Syrian state TV aired what it said was security camera footage of the blasts. In the first, a white van is driving on the road outside the military headquarters, then veers to the right and explodes. The second blast goes off inside the compound, with flames rising from behind trees.

Later, the army command building is seen engulfed in flames that sent huge columns of thick black smoke over Damascus for several hours.

The explosions shattered the windows of the Dama Rose hotel and other nearby buildings, as well as windshields of parked cars. Footage by another state-run TV channel, Ikhbariya, showed heavy damage inside the compound, with glass shards scattered across the floor and broken ceiling tiles.

The blasts caused fear among residents of a nearby upscale district, which has largely been sheltered from the violence that plagues other parts of the city.

"What if a random bullet killed one of my kids?" Nada, a 42-year-old mother of three who only gave her first name out of security concerns, said, crying over the telephone. The windows of her apartment were shattered and her furniture was damaged. "I only care about my children and I'm afraid of the gunfire," she added.

Gaith, 63, a retired civil servant who also just gave one name for the same reason, said he rushed to lock the gate of his building to keep rebels from hiding inside. "I don't want my place to collapse on my head," he said.

A Syrian army statement said "terrorists" -- a term the regime routinely uses for the rebels -- in the area simultaneously opened fire randomly to scare people, adding that authorities were pursuing the gunmen.

Witnesses said the explosions were followed by heavy gunfire that stretched on for hours near Omayyad Square and around the military compound. One witness reported seeing panicked soldiers shooting in the air randomly as they ran.

A group of army soldiers standing outside the buildings shouted pro Assad slogans, including: "Shabiha, forever, for your eyes, Oh Assad!" in reference to pro-regime militiamen.

Information Minister Omran Zoubi played down the rebels' ability to strike the nerve center of the Assad regime's battle for survival.

"Everything is normal," he told Syrian TV, which is near the army command center, in a phone call. "There was a terrorist act, perhaps near a significant location, yes, this is true, but they failed as usual to achieve their goals."

Zoubi initially insisted there were no casualties. However, Syrian state TV later reported four army guards were killed and 14 people were wounded, including civilians and military personnel.

The Iranian English language Press TV said one of its correspondents, 33-year-old Maya Nasser, a Syrian national, died in an exchange of fire in the area following the blasts. Another journalist working for Iranian Al-Alam TV was wounded, according to the station.

Press TV said Nasser was shot and killed by a rebel sniper while reporting on air. The station's newsroom director Hamid Reza Emadi blamed Turkey, Saudi Arabia and Qatar because they "provide weapons and militants to kill civilians, military personnel and journalists."

Iran is a supporter of the Syrian regime, while Turkey, Saudi Arabia and Qatar back the rebels.

Damascus, the stronghold of the regime, has been targeted repeatedly by the rebels. Previous bombings raised concerns that the al-Qaida terror network is becoming increasingly active in Syria. Jebhat al-Nusra, an extremist Syrian group, claimed responsibility for many of them.

On July 18, rebels detonated a bomb inside a high-level crisis meeting in Damascus that killed four top regime officials, including Assad's brother-in-law and the defense minister. Other large blasts have targeted the headquarters of security agencies in the capital, killing scores of people this year.

In other developments Wednesday, two activist groups monitoring casualties said dozens of bodies were found in a southern Damascus suburb. The reports could not be independently confirmed because of strict restrictions on foreign media.

The Britain-based Syrian Observatory for Human Rights said 40 bodies, including some of women and children, were found in the suburb of Thiyabiyeh. Rami Abdul-Rahman, the head of the Observatory, said he did not have details about how the victims were killed.

Another group of activists, the Local Coordination Committees, said 107 bodies were found, including women and children killed execution-style. It said the dead included nine members of the Al-Rifaie family whose throats were slit.

An amateur video, which could not be verified, showed the bodies of 18 men lined up on the floor of a room, some of them with marks of deep wounds.